Overseas buyers were responsible for half of the 10 largest mergers and acquisitions with US targets this month, led by the $7.5bn (€5.1bn) offer for a stake in Citigroup by Abu Dhabi Investment Authority, the world's largest sovereign wealth fund.

At the beginning of this month, Citigroup agreed to sell the Abu Dhabi group equity units that will convert into new shares giving it a maximum 4.9% stake in the US bank.